Fuse #6 Keeps Blowing!

Looks like you have it on the run. See if you can disconnect the linkage from the motor first. (I’ve never looked at these, so can’t offer any ideas). Then check the motor running. I would suggest checking current with linkage disconnected also.
If still blows the fuse, then sounds to me like the motor is bad.

Mark

Look for melted or heat damaged wires/insulation in the harness, plugs, and around the motor. The plug on this harness section is not waterproof, and can be subject to corrosion, especially in places that use salt on the roads. A high resistance connection could cause issues. The motor itself has two bearings (one at each end) and a gear drive I have not worked on this unit in detail, but you can inspect for signs of corrosion, or lack of lubrication.


The wiper pivots can be oiled by spraying or dripping some down the shaft. The various other parts of the linkage can be greased/lubricated by hand from the engine compartment.

Yes, you could check the resistance between the various pins on the motor...

...but it will be pretty low, even for a happy motor (under 2 ohms would be my guess).

With inexpensive ohmmeters and crappy/iffy probe-on-pin connections in the cold, the probe-to-pin varying resistance will probably swamp whatever the "truth" is.

--dick (but try it)

If the (preferably very small) fuse survives without the motor connected, then there’s less chance of a wiring or switching problem, and you should look for a problem with the motor or its load.

Electric motors draw more current as their loading increases, so it sounds like the motor could be overloading, however the fact it is blowing its fuse IMMEDIATELY suggests that it’s jammed or has an internal electrical problem within the motor.
The escalating frequency of the fuse blowing, and with a cold-weather climax, suggests that the wiper loads are growing for some reason. So things like the wiper stem bearings, linkages, etc. or simply the motor bearings may be getting stiff from wear or from their lubricant gelling up.

If you don’t want to get an ammeter to measure the motor current, you can still pull the motor linkage off and power it directly from a set of jumper cables (if it burns out with no external loads... well, you’ve found your problem ;-). The motor should run without labouring under its own friction, and the linkages and wiper arms should move easily and smoothly.

If anything fails to move freely and smoothly by hand, then do your best to free up and lubricate their bearings. They’re just rods in a tube with grease, but dirt and dried grease can make them stiff and too hard for the motor to move without stalling and drawing an excessive amount of current.

Good luck!

-dave

You might also try supplying 12v to the motor via some jumper wires directly from the battery. Doing this would isolate the motor from the other harness wiring, and give you a chance to eliminate the motor from the list of possible culprits (if it works normally with the jumpers supplying power). I like keeping a few lengths of 10-12 ga wire with alligator clips attached to both ends in my toolbox, for just this kind of diagnosis. Use the biggest wire you have handy. I would not reccomend using less than 14ga wire for such a jumper. Light gauge wire will get hot, or melt the insulation with too much current through it. Better to make one up with 10 ga wire, that will cover most of the circuits youll find, with enough capacity not to melt. If you dont find any melted insulation, etc on the supply wires to the motor, then check the connectors. Also check the ground. Either supply or ground wires can have corrosion, bad contact, eroded terminals, etc. The jumper can also be used to narrow down where the fault lay by connecting one end to motor as temporary power supply, then connecting (tapping)into the original supply wire by piercing the insulation with a straight pin, or drapery pin (with t shaped head) at various point along the original supply. Eventually, you will find a point in the original harness supply to the motor, where you have enough current to run the motor without blowing the fuse. Your problem is betwe een the motor, and where you poked the supply wire, and found enough current capacity to run the wiper motor. Just like corrosion on your battery terminals, you are looking for extra resistance (in this case- it really presents the symptoms of a dead short- where the positive motor supply is grounding itself out.) My spidey sense would be looking hard at every inch of the wire from the motor back toward the battery for a chafed bit of insulation. I seem to recall there are some areas where this kind of mechanical damafe is common. I recollect under the drivers seat, there is a bundle of wires that can chafe. The jumper can isolate the fault pretty quickly, i bet.

Also, if you have a mulimeter that can read resistance, you can connect one end to the positive wire in the motor supply harness, and the other end of the multimeter to ground. If you have zero or very low resistance, then you have confirmed a dead short to ground (likely the supply wire has rubbed a metal part of the van which is grounded- all the metal shares a common ground). I would also advise checking the resistance from the ground side of the motor connector to an actual ground. If the resistance is more than 1000 ohms, you have a bad ground. Often, the ground side of the circuit is overlooked when searching for faults. Do any resistance measuring with the battery disconnected. Measuring resistance, and stumbling on 12v is a sure way to blow a fuse in your meter (if it has one) some such fuses are inside the meter, soldered to pc board. A bad ground can cause the load (in this case the wiper motor) to draw more current than usual in order to run. My experience strongly suggests a chafed wire that can intermittently short to ground. Vibration, and vehicle motion can cause a fault like this to come and go.

Solved! - Re: Fuse #6 Keeps Blowing!

SOLVED!

Thanks for all the help everyone! As usual, this forum (and all of you on it) has proved its worth!

In the end, the problem was indeed that the wiper linkage was binding up. Much appreciation for the troubleshooting steps!
I started by undoing the mechanism and just running the motor; it ran fine. Then came to finding the problem, which seemed certainly to be a binding issue.

All of the joints were a little bit sticky, but nothing problematic. I lubed them up anyway (for the future,) but to no avail for the current problem. Then I noticed that at the very beginning of the wiper cycle, the motor crank arm was making contact with the bracket that holds the motor in place. There are two metal bumps on the bracket, and the crank arm was completely unable to move because of that. It was tough to notice at the beginning, as it only made contact when the bolt holding the crank arm onto the motor was fully torqued down, and in troubleshooting I had removed the assembly from the motor.

The fix!
In typical "outback mechanic" fashion, my final solution was to add 3 washers in between where the motor and motor crank arm connect. This raised the crank arm just enough to clear the two metal bumps. Should be good to go now! I put a 20A fuse back in (as specified), in place of the 30A, and it's all running smoothly!

I remember the previous owner telling me that he had recently replaced some pieces of the wiper linkage. Perhaps he had installed it slightly incorrectly which was stressing out the parts and forcing them to bend lower, which eventually made contact and bound up, blowing the fuses.

Onwards! Got my Mercedes grill in the mail, so maybe I'll put that on next to celebrate.

Photo 1: Wiper diagram.
Photo 2: Motor crank arm disconnected, showing where it attaches to the motor.
Photo 3: The fix! Washers...

Thanks everyone!

---

(I also found this little website helpful in my research about electric motors: https://inspectapedia.com/electric/Electric_Motor_Diagnosis.php)

I'm experiencing the same problem ! did you ever figure out what it was? how to fix it?

First let me extend to you a hale and hearty welcome to the forum.

Braxtonhstevens said:

I'm experiencing the same problem ! did you ever figure out what it was? how to fix it?

Click to expand...

From the post that you just replied to...

theOMsound said:

SOLVED!

Thanks for all the help everyone! As usual, this forum (and all of you on it) has proved its worth!

In the end, the problem was indeed that the wiper linkage was binding up....

All of the joints were a little bit sticky, but nothing problematic. I lubed them up anyway (for the future,) but to no avail for the current problem. Then I noticed that at the very beginning of the wiper cycle, the motor crank arm was making contact with the bracket that holds the motor in place. There are two metal bumps on the bracket, and the crank arm was completely unable to move because of that. It was tough to notice at the beginning, as it only made contact when the bolt holding the crank arm onto the motor was fully torqued down, and in troubleshooting I had removed the assembly from the motor.

The fix!
In typical "outback mechanic" fashion, my final solution was to add 3 washers in between where the motor and motor crank arm connect. This raised the crank arm just enough to clear the two metal bumps. Should be good to go now! I put a 20A fuse back in (as specified), in place of the 30A, and it's all running smoothly!
...

Click to expand...

Note that he thinks that the previous owner had repaired/replaced some parts. Historically his problem has not been a common issue.

vic

,!!!??!!

Hey all, unfortunately I'm back. I had no issues for quite some time, until now.

I was driving all day this week in the rain and about halfway through the day I noticed that the wipers were off centre. Meaning they started in the middle by wiping down, then back up, to the edge, repeat. The home position was halfway up the windshield, instead of at the bottom like it should be. Later that day, assuming the problem was just a loose not, I loosened the assembly attachment fully, re-centered it, and tightened it down.

Now, as soon as I turn the key, the fuse blows. With the motor unplugged it's fine, so we know the issue is with the motor itself. I tried it with the motor removed from the bracket completely and not attached to anything and it still blew instantly, without even having the wipers turned on in the cabin. (Could the motor be stuck "on?")

I took apart the motor and I don't know much but the magnet area seemed fine. The other part with the slow gear was very greasy but I don't know what to look for. I can turn the motor with a vice grip and it's quite stiff. I don't hear grinding or anything but I'm not sure how easy it should be to turn. You have to use some muscle.

Any ideas of how to fix it? Or should I just soak the 200 bucks and get a new one.

Thanks again for all the help.

See photos for inside motor. Let me know if you need different angles.

FINAL UPDATE:
I don't know EXACTLY what happened, but the issue is solved. When I re-set the mechanism to line everything up so that the wipers would be in a good position, it seemed like things were in a different placement than they had been before. When I ran the motor it looked like it was turning in the opposite direction (don't have video to remember unfortunately). My best guess is that somehow my motor was slowly dying, and at this point the stress on the motor may have caused a short, which switched the polarity on the motor, causing it to run in reverse. My readjusting the mechanical parts worked temporarily, but eventually the motor died anyway.

I bought a used motor for $100 CAD, popped it in, re-aligned the mechanism, and all is well.